Been using mouse button 3 for years as my voice chat button, but the game doesn't support it for the in-game push-to-talk button. Been using ventrilo with my friends and now realizing that you can't unbind mouse 3 from being a camera move button. Anyone know if there's a way in console, or a fix to unbind it in any way?

Only thing you can do right now is remap your mouse3 button to a keypress (with something like autohotkey, some mouse drivers also support this) and then bind the new key that is now being send when you press mouse3 as the push-to-talk key.

I'm 5'11 so I have decently big hands and my Razer Deathadder seems to work just fine for this type of set up! 4/5 I used to certain twitch abilities (such as focus spells in WoW). They're not the lightest buttons to push down so it makes it more difficult for them to be push to talk keys for me.

I'm the same as everyone else here that uses M3 for VoIP, Medium sized hands (probably from playing console games from a young age) and quite a large mouse (RAT5). Using M3 does have it's disadvantages unfortunately for Dota2, for example: if you're tracking your hero (with F1) and try to talk to team mates it flicks between your hero and where your mouse was on the ground after you pressed it, it also causes the camera to sometimes lock onto heroes if you're tracking them by holding M1 on their portrait.

It sometimes means that my camera isn't optimally positioned right and I miss something happening next to me but I've used it as long as I've known what VoIP was so changing to another button just wouldn't feel right. Besides, every other button on my mouse is bound to something else :D

Good button because it allows you to still use your mouse and not have a finger on your keyboard tied up while talking. So you can still use your moves and coordinate with teammates at the same time. Used it in WoW for arena, really good.

But you can't use the RMB with your middle finger on M3. Or you can't use your LMB with your index finger on M3. M3 disables one half of your mouse. What good is movement if you can't click potentially necessary buttons?

Compare that to M4, M5, etc., which do not impact your ability to use the keyboard or your ability to use RMB, LMB, and M3. Alternatively, most of the buttons on the left side of the keyboard (even when depressed) allow you access to 1, 2, 3, 4, q, w, e, r, z, x, c, v, a, s, d, f, tab, ctrl, alt, shift, caps, tilde, etc. A keyboard button does disable some multi-key combos, but that's still preferable, in my opinion, to losing M1 or M2.

I see M3 as the worst of all possible evils. I'm just curious as to how it's a good choice under combat conditions.

But seriously, even after years of PC gaming, including a great deal of time in games that use the numpad for navigation, I don't think I have the strength or dexterity in my ring finger to properly operate M2 in stressful situations with a lot of mouse movement. (I also have big, broad hands with thick, medium-length fingers, so that might factor into it.)

No idea why they put it in there in the first place but you have to change the config. cfg to get rid of it.
Go to
C:\Program Files (x86)\Steam\SteamApps\common\dota 2 beta\dota\cfg
and open the config.cfg. Scroll down until you find
bind "MOUSE3" "+voicerecord"
Delete the line and it should be working now.

Are you sure about that? What about the config_default.cfg?
I had exactly the same problem as you and deleting the line in the cfg file solved it for me.
As a kind of bruteforce method you can type voice_enable 0 in the dota console. It will disable any game voicechat but you can use your mouse 3 button for talking. Might be a solution if you play with a premade team most of the times.

Searched in both config files to no avail. Mouse 3 isn't anywhere to be found in the document and I searched it pretty thoroughly. Might be under a command name, so going to try turning 1s to 0s on a few of em and see what happens